One approach to rationality is to seek nirvana. To be free from all desires, for one side or the other. To let your mind be like a feather on the wind. This is the approach most rationalists seem to espouse. Another approach is to treat it as a struggle. Not to avoid motivated reasoning but to engage in it intentionally and forcefully. To realize that you can’t help but be biased and so to force yourself to think of and fully inhabit the cases/worlds for both sides of a debate.
I don’t know which approach is better. I don’t think they’re mutually exclusive.